(1) Field of the Invention
The present invention relates to a method for the dehalogenation of haloaliphatic compounds using pre-induced cells of Desulfomonile tiedjei or other sulfate reducing anaerobes In particular, the present invention relates to the degradation of tetrachloroethylene (perchloroethylene; PCE) and trichloroethylene (TCE) which are persistent environmental contaminants occurring in waste sites and groundwater.
(2) Prior Art
Contamination of groundwater by halogenated, particularly chlorinated, aliphatic hydrocarbons has led to concern over their environmental fate. Many of these compounds, including tetrachloroethylene (PCE), are anaerobically dechlorinated in the natural environment and by both methanogenic and sulfate reducing enrichment cultures as discussed by Bhatnagar and Fathepure (Bhatnagar, L., and B. Z. Fathepure, In J. G. Zeikus and E. Johnson (ed.) Biotechnology of Mixed Cultures, McGraw Hill, p.293-340 (1991); McCarty, P. L., In G. S. Omen (ed.), Environmental Biotechnology, p.143-162 (1988); and Vogel, T. M., C. S. Criddle and P. L. McCarty, Environ. Sci. Technol. 21:722-736 (1987)). The anaerobic dechlorination of PCE is of special interest since, unlike trichloroethylene (TCE) and lower substituted ethylenes, PCE is apparently not attacked by aerobic microorganisms. Little is known, however, about either the bacteria molecular mechanism involved in the reaction.
Desulfomonile tiedjei strain DCB-1 was originally isolated from an anaerobic enrichment growing on 3-chlorobenzoate (Shelton, D. R. and J. M. Tiedje, Appl. Environ. Microbiol. 48:840-848 (1984)). D. teidjei, a sulfate reducing bacterium, can obtain energy by using 3-chlorobenzoate as an alternate electron acceptor, producing benzoate and HCl as products (Dolfing, J., Arch. Microbiol. 153:264-266 (1990); Dolfing, J. and J. M. Tiedje, Arch. Microbiol. 149:102-105 (1987); Mohn, W. W. and J. M. Tiedje, Arch. Microbiol. 153:267-271 (1990)). Interestingly, D. teidjei was also found to dechlorinate PCE. In one recent study, D. teidjei produced significant PCE dechlorination among several pure cultures of anaerobes tested (Fathepure, B. Z., et al., Appl. Environ. Microbiol. 53:2671-2674 (1987)). Dechlorination of PCE by D. teidjei was found to be 2.34 .mu.molg protein.sup.-1 day.sup.-1 by Fathepure et al. (Fathepure, B. Z., et al., Appl. Environ. Microbiol. 53:2671-2674 (1987)), and 4 .mu.mol/l in five (5) months by Suflita et al. (Suflita, J. M., et al., J. Ind. Microbiol. 3:179-194 (1988)). These rates are slow.